TCP/IP Programming

I am a newbie, trying to program the TCP/IP protocol stack to complete a project for college. I would be grateful if somebody would tell me where to start from. I got some source code.. for the wattcp implementation. But can't make head or tail of it. So any helpful pointers would be greatly appreciated!Any suggestions on books to go through and online references would also be helpful. We are currently trying to work on both the Windows and Linux platforms..